That's the program that lets you skip paywalls and registration requirements -- from sites like the Wall Street Journal's -- when you're clicking through to articles from Google and Google News. (See here for instructions.)

For example, currently, Google users can read as many free WSJ articles as they want per day, assuming they're coming from Google. (This is very handy, and it has allowed me to cancel my WSJ.com subscription.) But Dow Jones now has the ability to limit it to five per user, per day.

This should still work for most people, but frequent readers may now have to think again about paying up.